Refrigerating apparatus actuated by a hot-gas engine



April 26, 1949. AK. nu PRE BEFRIGEF ."1

Nu' APPARATUS ACTUATED Filzd Jan. 3l, 1947 FRTS KAREL DU PRE A' TOMRNEY Patented Apr. 26, 1949 I 2,468,293 F ICE REFRIGERATING APPARATUS ACTUATm) BY A HT- Frits Kale! du Pr, Eindhoven, signor to Hartford National Company, Hartford, Conn.,

GAS ENGINE Netherlands, al- Bank and Trust as trustee Application January 31, 1947, SerlalNlo. 725,431

In the Netherlands February Claims.

This invention relates to a compact thermal exchange system; and more particularly to a combination of a refrigerating unit and a hot-gas engine unit in a compact device or heat-exchange system wherein a sealed pressurized or otherwise chamber containing coupling means is interposed between said units. A common thermal exchange medium is used in all the units and the said medium is also thermodynamically coupled to a like medium within the chamber, said thermodynamic coupling being made through means, part; of which is so positioned that the point of application of the pressure within said chamber to each working cylinder of each unit with respect to the cycle for each cylinder is so made that maximum eillciency for this combination is attained; more specically the invention relates to a com- ,bination of at least two thermal exchange engines integrated 'through a common fluid container. one engine being devoid of a prime heat source or sources and operating on the reverse principle of a hot-gas engine to produce a refrigerator.

This invention differently stated relates to a refrigerating system which is characterized in that it consists of a hot-gas engine and a cooling machine driven by the former and operating according to the reversed hot-gas engine principle, in which both the working space of the hot-gas engine and that of the cooling machine are connected to a common closed space, from which the same medium is obtained for both of them. By operation according to the reversed hot-gas eni gine principle is meant operation in which a gaseous fluid, for example air, is alternately compressed and expanded in separate working chambers having variable volumes and operating at different temperatures. In contrast to a hot-gas engine in which heat is working chambers and mechanical power is produced by the said compression and expansion of the gaseous fluid, in a refrigerator operating according to the reversed hot-gas engine principle, the compression and expansion of the gaseous iiuid is effected by externally applied mechanical power. A discussion of the thermodynamics of the hot-gas engine and the reversed hot-gas engine principle of operation may be found in the publication Philips Technical Review," May 1946, vol. 8, No. 5, pages 129 to 136.

In the present case a closed space is to be understood to mean a space which, in a, certain respect, is suiiiciently separated from the open air. This separation may iirstly be a separation between two diiierent media of equal pressure to avoid mixing viz. if a different medium than air is used in the working spaces of the cooling aggregate according to the invention and secondly it may be a separation which is capable of compensating a difference in pressure, which may occur if use is made of air under pressure as a working medium. It will be obvious that in the last-mentioned case more stringent requirements applied to one of theY must, in general, be imposed on the separation than in the rst-mentioned case in order to prevent the required pressure from leaking away within a short time. In the case of a combination of the two said possibilities, when consequentlyy mospheric pressure outside is fuliilled.

Consequently, -the conditions imposed on the closed space" of a common chamber depend upon the choice of the composition of the heat conveying medium and of the pressure used.

The cooling system according to the invention has the advantage of being a very simple comblnation of a cooling engine and a driving motor or engine. Since both the hot-gas engine and the cooling engine operate on the same principle, though reversed as far as the cooling machine is concerned, the manufacture of the system is very much simplied when using similar parts for both, since a large number of component parts are adapted to be used both for the driving engine and for the cooling engine.

A simple construction is also promoted by using the same medium for both machines. In spite thereof an economic operation of each individual machine is not adversely affected. This might be expected on account of the fact that for both machines a medium having the same pressure is obtained from the said space or pressurized chamber, which might suggest equality of pressure o1' the medium in the working space of each machine. In this case the operation of each machine would depend upon one and the same pressure, whereas in connection with an optimum individual operation a, certain freedom in the choice of the pressure for each individual machine is desirable. Realizing however, that the so-called breathing port of hot-gas piston engines, which serves as is well-known, for replenishing the medium in the compression and expansion spaces, may be arranged in such manner that replenishment can be eiected at any desired moment, for example at the moment at which the pressure of the medium in the working space has a maximum, a minimum or an intermediate value, this can be readily ensured. The range between the maximum and the minimum value of the pressure is sumciently wide to permit a proper choice to meet the requirements of an economical operation both of the hot-gas engine and of the cooling engine together and each individually.

In a suitable form of construction of thecooling system or combination according to the invention the means for forming the closed space or common chamber forms part of the structural .lunction between the hot-gas engine and thecooling engine, while the coupling between them is housed in the said space. Such a form of construction is very suitable if the engine and the cooling engine are in alignment, the center lines of the cylinders of the two machines thus forming a straight line, and in this case the construction is very simple.

The closed space or chamber does not exclude, within definite limits,` a communication with the surrounding open air. Thus, it may be advisable to use, for example, a lter e. g. a moisture absorbing filter, if the medium in the closed space consists of air of atmospheric pressure. In this manner any pressure differences can be compensated only via the filter, so that there is no risk of moist air penetrating into the closed space, which could bc harmful to the operation of the machines.

In certain cases, for example, if use is made of a medium other than air and at a different pressure, it may be necessary to seal the closed space hermetically from the open air. In this case use is preferably made of a form of construction in which the starting mechanism for the hotgas engine is housed in the closed space itself and passes through the wall thereof, the area of the lead-through being provided, if necessary, with an additional seal from 'the open air to ensure hermetic sealing. It may, for example, consist of a loose cap which is placed over the lead-through and the part adapted to be coupled with the starting device. J

An important object of this invention is to provide a combined hot-gas engine and a refrigerator unit mounted on a common base containing a reservoir holding a common thermal exchange medium of a pressure which may or may not be of that within the working cylinders of the respective engine and refrigerating unit. and which common thermal exchange medium is connected to the respective cylinders.

Another important -object of this invention is to provide a common pressurized chamber interposed between two thermal exchange units, one operating on the reverse r`rinciple of the other, for the introduction of the pressure within the common chamber to the respective units at a predetermined point in the cycle of operation of each so as to produce maximum thermal eiliciency.

A further primary object of this invention is to provide a heat exchange system in which one of the units thereof works reversely thermally from one of a prime mover in said system.

Another object of this invention is to provide a combination of a hot-gas engine unit and a refrigerator unit so arranged that a common reservoir may be employed to supplement the pressure within each of these units at a predetermined point in the cycle of operation of each for the production of a very eflicient heat exchange system.

Another important object of this invention is to provide a thermal exchange system in which a refrigerator constructed in the form of a hotgas, engine operates on the reverse normal principle of thermal exchange for the same and is provided with a prime mover of the hot-gas engine type, wherein a common tank or chamber is interposed between said prime mover and the refrigerator, and the prime mover is supplied with an external starting device having scalable means.

Further objects, features and advantages of this invention will become apparent as the description proceeds hereinafter.

The drawing shows a cross-sectional view along a longitudinal axis of one embodiment of the invention. Referring to the drawing it is seen that the present heat exchange system comprises a. hot-gas engine unit I0, a refrigerator unit IIR mounted on a common combined crankcase or a base I3. A study of the drawing will show that in many respects the construction of the hot-gas engine unit I0 is similar to that of the refrigerator unit IIR and, therefore, like elements are labeled with the same numberwith the letter R thereafter to distinguish between the parts of the two distinct thermal exchange units. For the purpose of facilitating the assembly of these distinct units the base member I3 is split along a vertical axis I -I and the two parts formed by such splitting are joined after the assembly of certain interior parts of the engine to be described hereinafter by any well-known fastening means such as bolts (not shown). Base member I3 is so formed as to provide a cavity or chamber I4 which may or may not be pressurized and which constitutes the closed space referred to above. A purpose of this chamber is to house coupling means I2 as well as to act as a common chamber for both units IIJ and I IR.

Substantially centrally located within chamber I4 there is lfound a common wobble plate drive consisting of a wobble plate I5 assembled on a crankshaft I6 by means of a split bearing and journalled in bearing I1 and IIR within the common base member I3. A pinion I8 splined on the left end of crankshaft I6 is coupled to a rack gear 2I in a starting device to be described in detail hereinafter. The particular hot-gas engine selected for the prime mover in theI embodiment of the invention is of the four cylinder four-cycle engine type operating in accordance with the principles set forth in the U. S. patent application Serial No. 614,347 filed September 4, 1945 of Franciscus Lambertus van Weenen. The hot-gas engine shown comprises four cylinders 34. Within each cylinder there is provided a piston 24 having an operative surface 4'IJ which together with the cylinder 34 defines a heater chamber 4I and having an operative surface 42 which together with the cylinder defines a cooled chamber 43. The cylinders are arranged in a square in spaced relationship with their axes 34 parallel to the axis of the crankshaft I6 whereby each of the pistons are operatively connected to the wobble plate mechanism I5 through rods 23, the said pistons being thus positioned with a phase displacement approximately relative to each other. As the pistons 24 reciprocate, the wobble plate mechanism I5 undergoes a wobbling motion' which results in a rotary motion of the crankshaft I6. In accordance with the principles set forth in the above-referred copending application of F. L. van Weenen the hot chamber 4I of one cylinder 34 is connected through a heater 33, a regenerator 35, a cooler 31 and a conduit 4'4 to the cooled chamber 43 of an adjacent cylinder 34, forming thereby a closed system between two adjacent cylinder means; the hot-gas engine thereby having a total of four such closed systems. A working medium such as air, is contained within each closed system. External heaters and coolers 30 and 45 respectively are associated with the hot chamber and the cold chamber of each closed system. The operation for each cycle of the hotgas engine is as follows: the work medium which is first compressed and cooled in the cold chamber heated and expanded to a maximum volume. It

is then passed at maximum volume through the regenerator from whence it leaves with a certain temperature drop to the cold chamber. where it is cooled and compressed to the initial minimum volume after which the cycle is repeated. As 'a result of the thcs oi the cycle, heat energy is transformed into mechanical energy.

' The refrigerating unit IIR similarly comprises four cylinders 34B arranged in a square with their axes coincident with the axes of the cylinders 34 of the hot-gas engine. The remaining structure, with the exceptions notedI is similar mechanically to the hot-gas engine above described and similar parts are indicated by the same numeral followed by the letter R. Similarly, the cycle of operation takes place between working surfaces of the pistons of two cylinders whereby the gaseous working fluid -ilows from a chamber 4IR of one cylinder 34B, a heat absorber NR, regenerator 3ER and cooler 31B. through a conduit R to the space 43R ci another cylinder SIR.

The operation for each cycle of the refrigerator unit is as follows. compressed in a space 43R of one cylinder and transferred by means of the conduit R through the cooler 31R asociated with another of the cylinders 33R. In the cooler 31R the heatiof compression is removed from the gas and the gas flow continues through the regenerator 35R and heat absorber 33B. to the chamber AIR. Within the chamber GIR the gas is expanded and in so doing its temperature drops. The so-cooled gas returns through the heat absorber 33B, and by means of the thermal exchange therethrough cools the contents of the casing 4BR.

The amount of air in any cycle is one factor which determines the amount of power developed by the hot-gas engine, and the amount of refrigeration developed in the reverse hot-gas engine cycle.

In order to produce a compact thermal exchange system in accordance with the inventors concept, the thermal exchange assembly 22 of the hot-gas engine is mounted on the base member I3 in opposed relation with a similar thermal exchange assembly 22R of the refrigerator unit and to this end connecting rod means 23 are shown connecting the piston means 24 and 24R of the respective units. The distinct thermal exchange units It and IIR lbeing of the double acting type, only one piston means is shown in each of the named assemblies 22 and 22R, connecting rod means 23 being a direct drive between piston means 24 and 24R. The assembly of the same may be made simple by breaking the connection vbetween these pistons by any convenient expedient such as a threaded connection means (not shown) but which any skilled mechanic could supply.

The gaseous working uid is Y Connecting rod means 23 ride in substantially gas-tight bearings I9 and ISR which are aligned. Of course, it should be realized that the inventor does not wish to limit his concept to a four-cycle four cylinder prime mover drive as it can be readily understood that the more commonly known hot-gas engine drive employing both a displacer and a piston may be used; in which case only one hot-gas thermal exchange assembly 22 may be used with one or more refrigerator unit thermal exchange assemblies depending upon the selection of the type of coupling means used.

It also can be readily understood that the wobble plate driving mechanism included in the coupling means or driving means I2 could be substituted by the similar crankshaft drive. The bearing would in that case be at right angles from that shown already in I1 and I1R. Each of the hotgas engine units 22 comprising the total unit I0 consists of cylinder 34 to which is attached at the left hand end an inner heater 33 of corrugated material at which exteriorly is attached also a heater head 32, the latter forming a chamber at the left hand open end of the cylinder '34. These named parts comprise the interior portion of a heater assembly 30 which exteriorly includes a corrugated metallic material 3l of good conductivity bonded to the exterior of the heater head 32. All these parts are heated by prime heat source 25. f

At the right or open end of heater head 32 a cooler assembly 31 comprising inner and outer corrugated members similar to members 33 and 3l respectively are attached thereto. Since these details of the construction of the hot-gas engine thermal exchange assembly 22 do not constitute the present invention further discussion of the same is not necessary. An insulation member 36 having symmetrically spaced holes into which each hot-gas engine component 22 may be introduced at the region of the regenerator 35 interposed between the heater 30 and the cooler 31, provides the proper thermal division between the base or crankcase I3 and the well-known hot chamber of each said component 22. A similar insulation member 3BR is located on the refrigerator end of the novel heat exchange system, but since each component 22R of the refrigerator unit- IIR is identical as far as the engine unit 22 par se is concerned, discussion of elements 3IR, 32B, 33R, 34R, 35R and 31R corresponding respectively to elements 3|, 32, 33, 34, 35 and 31 in the prime mover I0 devoid of burners 25, of course, is unnecessary. However, it should be noted that an additional U-shapd insulation member 4BR joined to member 3BR to complete a casing around the compressor section of the refrigerator unit IIR is supplied to isolate this section thermally from the expansion or cooler section of the unit IIR.

The above described thermal system permits the use of a heat conveying medium common to both prime mover unit I U or units 22 and refrigerator unit I IR or units 22R because of a common chamber I4' interposed between these distinct units; distinct as far as their respective functioning is concerned. If air at atmospheric pressure is used, a iiiter 2, having moisture absorbing properties and made of well-known materials such as calcium chloride, placed in an opening in the bottom wall of the combined crankcase and chamber means I3 may be used as a pressure balancing agent and moisture remover.

Another important aspect of the invention concerns the thermal eiiiciency of the thermal system from a pressure viewpoint. It has been demonstrated elsewhere in many known patents that the emciency of a hot-gas engine can be raised under definite load conditions when the working pressure of the engine is augmented by an external pressure at a predetermined point in the engine cycle. However, a phase of the present inventive concept carries this idea much further by virtually joining two distinct thermal exchange units to a common tank so that a common pressurized liquid-and/or gas medium or media may 4be used in attaining the named augmented pressure. Since the resultant structure or heat exchange system is virtually e sealed system, expensive but highly conductive, `and low molecular weight media may be employed to raise the thermal emciency of the system by that source alone. To allow the pressure of closed space I4, which may be four to five atmospheres, to exert itself at the proper moment in each working-cylindermeans of each thermal exchange unit such as 22 and 22R, channel means 'I and 1R are led to a predetermined section of cylinders 34 and 34B. respectively from the common closed space I4 whereby the gaseous working fluid of the four cycles of the refrigerator and the gaseous working iiuid of the four cycles of the hot-gas engine are interconnected to the common space I4. Of course, in this construction, once the named section is selected and the channel means is built in accordance with such selection, the efliciency of the subject thermal system is unalterable thereafter. However, this can be easily solved by employing the type of pressure control for both the prime mover engine I and cooling engine IIR found in patent application Serial No. 615,044 flied September 7, 1945 of Pieter Hajo Clay (deceased).

The operation of the four-cycle hot-gas engine I0 having already been described in the specification above as well as in the referred to patent application Serial No. 614,347, and since the motivated engine, the cooling engine or refrigerator unit I IR operates on the reversed hot-gas enginev principle, the functioning of the present thermal system which combines these distinct engines in the manner described should be clearly understandable to one versed in the art.

The problem of externally starting the prime mover I0 is solved by a simple arrangement of a rack gear I8 mounted at an inward end of an externally protruding rod 8 sealably fitted through a packed bearing 3, 4 the latter element of which bearing is externally threaded and may be made an integral part of the crankcase I3. A cap 9 is threadedly placed over the outside of this bearing when a starting mechanism including these parts and gear I8 is not actually used. By moving rod 8 the proper position of the working pistons 24 within the external or hot-gas engine I0 can be attained for prompt starting of the engine once the heaters 30 heated from prime heat sources 25 have reached the proper temperature.

What I claim is:I i

1. A cooling system comprising a hot-gasgengine, anda cooling machine driven by the former and operating on the reversed hot-gas engine principle, and common closed-space forming means, both the working space of the hot-gas engine and that of the cooling machine being connected to said common closed space from which the same medium is obtained for both machines.

2. A cooling system as claimed in claim 1, wherein the means forming the closed space forms part of the structural junction between the hot-gas engine and the cooling machine, while the coupling between them is housed in the closed space.

3. A cooling system as claimed in claim 1, wherein the closed space communicates with the surrounding open air through a filter.

4. A cooling system as claimed in claim 1 wherein the hot-gas engine comprises a starting mechanism which is housed in the closed space and taken out through the wall thereof, the leadthrough being provided, with an additional seal from the open air.

5. Apparatus as described comprising a hotgas engine, a cooling engine operating on the reversed hot-gas engine principle, means forming a base for said enginesand a chamber for a common thermal exchange medium interposed between said engines, cyclically operating means joining each of said engines to said chamber and driving means coupling said engines, part of said driving means being found within said chamber.

6. A refrigerator device comprising a first hotgas engine, a second hot-gas engine adapted for operation on the reverse heat exchange principle of the first engine, chamber means common to both engines interposed between said first and second engines, means coupling said rst engine to said second engine, and means cyclically connecting the interior of each of said engines to the interior of said chamber means whereby a thermal exchange-medium common to said engines and said chamber interior may exert its pressure as found in said chamber interior at a preselected moment with respect to an engine cycle for the attainment of maximum efficiency.

7. A heat exchange system comprising an external combustion engine, a second similar engine adapted for reverse thermal operation to constitute a cooling machine, a compound base and common closed space means interposed between said engines, movable means mechanically coupling said engines, rnedium conveying means coupling each said engine to said compound base and space means, external starting means coupled to said movable means, and means for sealing said starting means.

8. A heat exchange system as claimed in claim 7 wherein lter means joined to said space means cause air to breathe into said space during part o f the time in which said system is normally functioning.

9. A heat exchange system comprising a hotgas engine unit with piston means, a refrigerator unit with piston means opposed to said first piston means and including a hot-gas engine thermal exchange assembly operating on the reversed hot-gas piston engine principle, common combined crankcase and thermal medium confining means aligned between said hot-gas engine unit and said refrigerator unit, said combined means having aligned bearing means, and coupling means, parts of which are within said crankcase, interconnecting opposed piston means of said units respectively.

10. A heat exchange system comprising a hotgas engine having piston means, a refrigerator unit having piston means, a common combined crankcase-bearingand liquid-confining means interposed between said engine and said unit, and means coupling said engine piston means and 'said refrigerator unit piston means together through said combined means whereby a compact system is produced.

FRITS KAREL DU PRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,240,862 Lundgaard Sept. 25, 1917 1,475,234 Lundgaard NOV. 2'7, 1923 2,272,925 Smith Feb. 10, 1942 

